Abstract: This paper proposes a novel active control method implemented by using Genetic Algorithm (GA). Based on the discrete motion equation of a multi-freedom degree system with time delay, the method is to optimize an appropriated controlled gain by using GA. The approach can solve such subsistent problems as effective control for a seismically excited structure with an explicit time delay under an explicit objective. Finally a series of computed results are given to prove that the proposed method is capable of providing a satisfactory control effect with different time delay.